The invention relates to a substance exchange device for intracorporeal use, comprising a cavity for receiving blood having at least one blood inlet and at least one blood outlet, a substance exchange membrane adjoining the cavity, a supply duct for supplying an exchange fluid to the substance exchange membrane, a blood pump arranged within the cavity and a drive unit for the blood pump, wherein the blood pump is configured to pump blood in a direction from the blood inlet to the blood outlet of the cavity.
In this context, a substance exchange device is any device for exchanging substances from blood or into blood. The substance exchange membrane may have a first side and a second side opposite the first side, wherein the first side may adjoin the cavity and wherein the supply duct may be configured to supply the exchange fluid to the second side of the substance exchange membrane. An exchange substance contained in or corresponding to the exchange fluid may pass over the membrane into the blood on the other side or, the other way round, an exchange substance may pass from the blood into the exchange fluid. During operation the blood pump may be used to create a local pressure difference between the blood inlet and the blood outlet to enable the required blood flow via the membrane. Otherwise, there would hardly be any blood flow via the membrane due to its flow resistance. By virtue of the blood pump, the pressure loss caused by the substance exchange device is compensated at least in part. In particular, the blood pump may enable the blood flow via the membrane and increase it along the substance exchange device, and optionally the blood flow may be supported by a bypass arranged upstream of the membrane.
The blood pump may be any conveying device which is configured to at least partially compensate for a pressure difference between the blood inlet and the blood outlet during operation. The conveying device may comprise a drive unit for generating a torque and a pump rotor connected with the drive unit for the transmission of a torque. For example, the drive unit may comprise an electric motor. That achieves a simple control of the conveying device, in particular of the rotational speed of the rotor.
Substance exchange devices, such as intravascular membrane oxygenators, are known from patent documents in different embodiment variations. For example, WO 2004/016300 A2 discloses an intravenous oxygenator configured as a catheter for oxygenating the blood, having a membrane in the form of a fibre bundle, with each of the fibres connected to a gas supply via a first port and to a gas exhaust via a second port. The fibre bundle is torsion-bent by a relative twisting of the first port of the fibres with respect to the second port of the fibres around the longitudinal axis of the oxygenator during operation. As a consequence, the fibres extend along the entire length of the fibre bundle as continuous gas conduits. During operation of the oxygenator, oxygen is supplied, flowing into the fibres via the first port and causing a diffuse gas exchange with blood on the surface of the fibres. During this, the blood is enriched with oxygen while CO2 is being removed at the same time. Consequently, a gas mixture of oxygen and carbon dioxide is present in the fibres at the second port, which mixture flows through an exhaust chamber in a tube and out of the patient's body through the tube. The blood flowing into the oxygenator passes through the torsion-bent fibre bundle and reaches a pump. Here, the blood is conveyed in the flow direction of the vein and leaves the oxygenator through an outlet. Thus, the pressure drop of the blood is compensated for by the pump, so the pressure at the outlet equals the physiological pressure again.
Only marginally, US 2010/258116 A1 mentions the use of a rotor, but without any indication of its use as a blood pump. The impeller is not presented in more detail and no executable technical solution on how to possibly arrange and drive such a rotor is given, so the function of the impeller remains unclear.
The pump shown in US 2013/053623 A1 serves to support the cardiac function and thus relates to an entirely different field of application than the present device. Naturally, the pump shown does not comprise a membrane as defined by the device according to the invention, i.e., for the exchange of substances.
In the device shown in GB 2505068 A, a blood pump is driven by a drive shaft of a drive unit located outside the body. This means that in this case the drive unit is not a part of the substance exchange device for intracorporeal use.